In a principal aspect the present invention relates to a method and apparatus for forming piers in various types of soil for the purpose of supporting a structure. The apparatus comprises an elongate, hollow tube structure with a shaped bottom head element and a mechanism for lateral expansion of a section of the hollow tube element adjacent the head element.
In U.S. Pat. No. 5,249,892, incorporated herewith by reference, a method and apparatus are disclosed for producing short aggregate piers in situ. The process includes forming a cavity in soil typically by a drilling process and then introducing successive layers of compacted aggregate material into the cavity to form a pier that can support a structure. The layers or lifts of aggregate are compacted during the pier forming process by means of a tamping device and typically have a diameter of 1–3 feet and a vertical rise of similar dimension.
U.S. Pat. No. 6,354,768, incorporated herewith by reference, discloses another method and apparatus for improving the stiffness of soil to support a structure. This method employs placement of an expandable member such as a bladder in the soil and subsequently expanding the bladder by pumping grout into it to compact the adjacent soil. The expandable member filled with grout or other material from the casing in the soil to serve as a pier.
U.S. Pat. No. 6,425,713, incorporated herewith by reference, discloses yet another methodology and apparatus for installation of a support pier. This patent generally discloses placement of a hollow casing in the soil and then removing material from the casing by means of a drill. Aggregate is then placed within the casing and the casing is manipulated to compact the aggregate to form a support pier.
While all of the foregoing methods and apparatus are considered to be useful for the formation of piers, there has remained the need to provide a method which will quickly and effectively enable construction of piers in multiple types of soils, including clay soils.